Flame retardant compositions for plastics



United States Patent 3,422,047 FLAME RETARDANT COMPOSITIONS FOR PLASTICS Joseph Frederick Cannelongo, Piscataway, N.J., assignor to American Cyanamid Company, Stamford, Conn., a

corporation of Maine No Drawing. Filed Jan. 19, 1966, Ser. No. 521,526 U.S. Cl. 26028.5 Claims Int. Cl. C08f 29/02; C08f 45/54; C09k 3/28 ABSTRACT OF THE DISCLOSURE This invention relates to flame-retarded compositions comprising a thermoplastic polymer containing a flameretarding amount of a synergistic combination of a chlorinated hydrocarbon material and a compound having the formula wherein R represents an alkyl (C -C radical, a cyanoalkyl (C -C radical, an hydroxyalkyl (C C radical, an aryl (C C radical or an aralkyl (C -C radical and R represents an alkenyl (C -C radical, an imidazoylalkyl (C -C radical, a carboxyalkyl (C -C radical, a dialkylaminoalkyl (C -C radical, a carboxyalkenyl (C -C radical, a carboalkoxyalkyl (C -C a carboalkoxyalkenyl (C -C radical, an alkyl (C -C radical, a cyanoalkyl (C -C radical, an hydroxyalkyl (C -C radical or an aralkyl (C -C radical and X represents chlorine, bromine or iodine.

The use of certain additives for the purpose of reducing the flammability of various thermoplastic polymers is well known to those skilled in the art. Among the additives currently employed for such a use are various specific types of phosphorus-containing compounds. These phosphorus compounds are generally used either alone or in combination with other materials such as aliphatic or aromatic antimonous compounds. Certain analogous materials such as chlorostyrene copolymers, chlorinated parafiin waxes, alone or with antimony oxide, are also known to be effective flame-retardants for resinous materials. One drawback of these known compounds and combinations of compounds, however, has been the fact that generally large amounts, i.e., upwards of 35%, of the additive must be incorporated into the polymer in order to render it reasonably flame-retardant. Such large quantities of additive ofttimes deleteriously alter the properties of the polymer and moreover, some additives tend .to crystallize or oil out of the polymer after a relatively short time of incorporation therein.

I have now found that superior flame-retarding properties can be imparted to thermoplastic polymers by incorporating into the polymer, a synergistic combination or mixture of a chlorinated hydrocarbon material and a compound represented by Formula I, above. The novel synergistic combination provides improved flame-retardance over the additives of the prior art and, additionally, provides this superior result at materially lower concentrations than previously found to be necessary for the known additives.

The results shown by the use of the above-mentioned flame-retardant combination are surprising and unexpected in that the combination provides a greater degree of flameretardancy than one would expect from the results shown by the use of the components individually, i.e. they are synergistic. Moreover, the combination produces a greater degree of flame-retardancy at lower concentrations in the polymer than could heretofore be achieved utilizing known materials. Additionally, the effectiveness of the combination is achieved in the absence of any third ingredient, such as antimony compounds which were previously believed to be necessary. This synergism, moreover, does not appear to be limited to specific combinations, but is broadly applicable to any combination of a chlorinated hydrocarbon material and a monophosphonium halide represented by Formula I.

It is therefore an object of the present invention to provide flame-retardant compositions.

It is a further object of the present invention to provide flame-retardant compositions comprising a combination of a monophosphonium halide and a chlorinated hydrocarbon material.

It is still a further object of the present invention to provide flame-retarded compositions comprising a thermoplastic polymer containing a flame-retarding amount of a synergistic combination of a chlorinated hydrocarbon material and a monophosphonium halide represented by Formula I, above.

These and other objects of the instant invention will become more apparent to those skilled in the art upon reading the more detailed description set forth hereinbelow.

As mentioned above, the first critical component of our novel flame-retardant compositions is a chlorinated hydrocarbon material. Although any chlorinated hydrocarbon material tends, to some extent, to be eifective, I have found that those which are stable to the processing conditions of the thermoplastic polymers when in com- :bination therewith are more preferable. That is to say, a critical limitation in regard to the chlorinated hydrocarbon materials is that they should have a boiling point of at least about 200 C., in that those of a lower boiling point tend to vaporize out of the polymer when it is ultimately processed or fabricated for consumer production.

A second critical limitation in regard to the chlorinated hydrocarbon materials utilized herein is that they must contain at least about 40% of combined chlorine, preferably from about 40% to by weight, based on the weight of the compound per se. Percentages of combined chlorine above 80% are tolerable but impractical, while at percentages lower than about 40%, the flameretarding effectiveness of the combination is materially lowered. The chlorinated hydrocarbon material may be used in concentrations ranging from about 0.2% to about 15.0%, by weight, based on the weight of the polymer to which it is added, preferably from about 0.5% to about 12.0%, same basis.

Examples of useful chlorinated hydrocarbon matenials include compounds such as perchloropentacyclodecane, hexachlorocyclopentadiene, hexachlorobenzene; the polychlorinated monocyclic aromatic hydrocarbons such as 2,3,5,6-tetrachloro-o, m or p-xylene, 2,5-dichloro-o, m or p-xylene, 0:,a-diChl0l'O-O, m or p-xylene, a,oc'-h6XaChlOI'0-0, m or p-xylene; various commercially available chlorinated biphenyls and polyphenyls which range in consistency from oily liquids to fine, white crystals to hard, transparent resins. These biphenyls and polyphenyls are nonoxidizing, have a low volatility and are non-corrosive. They are not hydrolyzed by water, alkalies or acids, are insoluble in water, glycerine and glycols and distill at about 215 C. to about 450 C. The crystalline materials have melting points up to about 290 C. and the resins have softening points up to about C.

A further class of applicable chlorinated hydrocarbon materials useful herein are the chlorinated parafiin waxes containing between about 40% to 80% combined chlorine and averaging from 18-36 carbon atoms. These materials 3 are chlorinated soft or slack waxes and are set forth in one or more of the following US. Patent Nos. 2,924,532, 2,962,464 and 3,194,846, which patents are hereby incorporated herein by reference.

The second critical component of my novel flame-retardant compositions is a monophosphonium halide represented by Formula I, above. These compounds, too, are suitable herein as long as they are stable to the ultimate processing conditions of the polymer into which they are incorporated. They may be produced by any known procedure, one of which is disclosed in U.S. Patent No. 3,005,013, also hereby incorporated herein by reference.

The monophosphonium halide may be incorporated into the polymeric material in concentrations ranging from about 0.1% to about 15.0%, preferably, 0.2%-12.0%, by Weight, based on the weight of the polymer to which it is added.

The terms aryl radical and aralkyl radical, as used herein in regard to substituents R and R of Formula I, above, are meant to include, not only carbon hydrogen cyclic compounds, but also lower alkyl, halo and cyano ring-substituted cyclic compounds and the scope of the instant invention should be construed so as to include compounds falling within this definition.

Examples of monophosphonium halides Which may be used according to the instant invention include tetramethylphosphonium chloride, bromide and iodide, tetraethylphosphonium chloride,

bromide and iodide, tetra-n-propylphosphonium chloride, bromide and iodide, tetraisopropylphosphonium chloride, bromide and iodide, tetra-n-butylphosphonium chloride, bromide and iodide, tetra-t-butylphosphonium chloride, bromide and iodide, tetraisobutylphosphonium chloride, bromide and iodide, tetrasecondarybutylphosphonium chloride, bromide and iodide, tetrapentylphosphonium chloride, bromide and iodide, tetrahexylphosphonium chloride,

bromide and iodide, tehraheptylphosphonium chloride, bromide and iodide, tetraoctylphosphonium chloride,

bromide and iodide, tetracyanomethylphosphonium chloride, bromide and iodide, tetra-2-cyanoethylphosphonium chloride, bromide and iodide, tetra-Z-cyanopropylphosphonium chloride, bromide and iodide, tetra-3-cyanopentylphosphonium chloride, bromide and iodide, tetra-Z-cyanohexylphosphonium chloride, bromide and iodide, tetra-4-cyanohexylphosphonium chloride, bromide and iodide, tetra-3-cyanoheptylphosphonium chloride, bromide and iodide, tetra-6-cyanooctylphosphonium chloride, bromide and iodide, tetrahydroxymethylphosphonium chloride, bromide and iodide, tetra-2-hydroxyethylphosphonium chloride, bromide and iodide, tetra-Z-hydroxypropylphosphonium chloride, bromide and iodide, tetra-3-hydroxypentylphosphonium chloride, bromide and iodide,

tetra-4-hydroxyhexylphosphonium chloride,

bromide and iodide,

tetra-6-hydroxyhexylphosphonium chloride,

bromide and iodide,

tetra-3-hydroxyheptylphosphonium chloride,

bromide and iodide,

tetra-8-hydroxyoctylphosphonium chloride,

bromide and iodide,

tetra-3-cyanobutylphosphonium chloride,

bromide and iodide,

tetra-3-hydroxybutylphosphonium chloride,

bromide and iodide,

tetraphenpylphosphonium chloride,

bromide and iodide,

tetratolylphosphonium chloride,

bromide and iodide,

tetraxylylphosphonium chloride,

bromide and iodide,

tetra-a-methylphenylphosphonium chloride,

bromide and iodide,

tetranaphthylphosphonium chloride,

bromide and iodide,

tetrabenzylphosphonium chloride,

bromide and iodide,

tetra-2-phenethylphosphonium chloride,

bromide and iodide,

tetra-4-phenylbutylphosphonium chloride,

bromide and iodide,

tetra-S-phenylpentylphosphonium chloride,

bromide and iodide,

tetra(o, m or p-chloro, bromo, fluoro or iodobenzyl)phosphonium chloride,

bromide and iodide,

tetra(o, rn or p-dichloro, dibromo, or diiodobenzyl)phos phonium chloride,

bromide and iodide,

tetra(o, m or p-chloro-Z-phenethyl)phosphonium chloride,

bromide and iodide,

tetra(o, m or p-dibromo-Z-phenethyl)phosphonium chloride,

bromide and iodide,

tebranaphthylmethylphosphonium chloride,

bromide and iodide,

tetra(alkyl, chloro, dibromo or cyano Ar-substituted naphthylmethyl)phosphonium chloride,

bromide and iodide,

carboxymethyltrimethyl phosphonium chloride,

bromide and iodide,

8-carboxyoctyltrioctyl phosphonium chloride,

bromide and iodide,

tris(3-hydroxybutyl)-8-cyanooctyl phosphonium chloride,

bromide and iodide,

tri-n-butyl-8-hydroxyoctylphosphonium chloride,

bromide and iodide,

trinaphthyl carboethoxy-l-butenyl phosphonium chloride,

bromide and iodide,

methyltriphenylphosphonium chloride,

bromide and iodide,

ethyltriphenylphosphonium chloride,

bromide and iodide,

propyltriphenylphosphonium chloride,

bromide and iodide,

benzyltriphenylphosphonium chloride,

bromide and iodide,

p-chlorobenzyltriphenylphosphonium chloride,

bromide and iodide,

2,4-dichlorobenzyltriphenylphosphonium chloride,

bromide and iodide,

carboethoxymethyltriphenylphosphonium chloride,

bromide and iodide,

tris (Z-cyanoethyl)methylphosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl)ethylphosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl) octylphosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl)vinylphosphonium chloride,

bromide and iodide,

benzyltris(2-cyanoethyl) phosphonium chloride,

bromide and iodide,

2,4-dichlorobenzyltris (Z-cyanoethyl) ph osphonium chloride,

bromide and iodide,

2,5-dichlorobenzyltris(2-cyanoethyl)phosphonium chloride,

bromide and iodide,

3,4-dichlorobenzyltris(Z-cyanoethyl)phosphonium chloride,

bromide and iodide,

2,4-diiodobenzyltriphenylphosphonium chloride,

bromide and iodide,

2,5-difluorobenzyltriphenylphosphonium chloride,

bromide and iodide,

3,4+dibromobenzyltriphenylphosphonium chloride,

bromide and iodide,

2-hydroxymethyltriphenylphosphonium chloride,

bromide and iodide,

tris(Z-cyanoethyl)-2-hydroxyethylphosphonium chloride,

bromide and iodide,

tributylbenzylphosphoniurn chloride,

bromide and iodide, V

tributylvinylphosphonium chloride,

bromide and iodide,

tributyl-2,4-dichlorobenzylphosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl)-0-cyanobenzylphosphonium chloride,

bromide and iodide,

tris(2-hydroxyethyl)-4-octenyl phosphonium chloride,

bromide and iodide,

cyanomethyltriphenylphosphoniurn chloride,

bromide and iodide,

2-hydroxyethyltrip-henylphosphonium chloride,

bromide and iodide,

tributyl[Z-(Z-methyl-1imidazolyl)methyl1phosphonium chloride,

bromide and iodide,

tricyclohexyl [2- (Z-methyll-imidazolyl) ethyl] phosphonium chloride,

bromide and iodide,

tributyl(diethylaminoethyl)phosphonium chloride,

bromide and iodide,

tris 2-cyanoethyl) (Z-methylnaphthyl) phosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl)-2,4- (dibromobenzyl)phosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl) (3-chloro-2-methy1-naphthyl)phosphonium chloride,

bromide and iodide,

tributyldimethylaminoethylphosphonium chloride,

bromide and iodide,

2-carboethoxypropyl triphenylphosphonium chloride,

bromide and iodide,

carbobutoxymethyltriphenylphosphonium chloride,

bromide and iodide,

dibutylaminoethyltrimethylphosphonium chloride,

bromide and iodide,

cyanomethyltrirnethylphosphonium chloride,

bromide and iodide,

trimethyl-3-carboxypropenyl-1-phosphonium chloride,

bromide and iodide,

triphenyl-2-carboxyvinyl-l-phosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl)-2-carbomethoxyvinylphosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl)-2-carbomethoxypropenyl-3-phosphonium chloride,

bromide and iodide,

tripheny1-4-carbomethoxybutenyl-4-phosphonium chloride,

bromide and iodide,

triphenyl-Z-carbomethoxypropenyl-3-phosphoniurn chloride,

bromide and iodide,

tributyl-Z-carbomethoxypropenyl-3-phosphonium chloride,

bromide and iodide,

tributyl-S-carbomethoxypentenyl-Z-phosphoniuin chloride,

bromide and iodide,

tris(2-cyanoethyl)-2-carboethoxyvinyl phosphonium chloride,

bromide and iodide,

tris(2-hydroxyethyl)-2-carbomethoxypropenyl-3-phosphonium chloride,

bromide and iodide,

tris(2-cyanoethyl)-3-carboxynonenyl-l-phosphonium chloride,

bromide and iodide,

tributyl-2-carboxyvinyl phosphonium chloride,

bromide and iodide,

mixtures thereof, other compounds having mixed substituents, and the like.

In general, any thermoplastic polymeric material may be rendered flame-retardant by the incorporation therewith of the above-identified flame-retardant combinations. Generally, however, the vinyl type polymers, wherein a monomeric material is polymerized, by known methods, e.g. by use of tree-radical generating catalysts, irradiation, anionic and cationic catalysts, etc. are those preferred. Examples of the vinyl type polymers which may be used to form my novel compositions are the polyvinyl acetates, polyvinylbutyral, butadiene copolymers, e.g. acrylonitrilebutadiene-styrene copolymers, the polyacrylonitriles, polybutadiene, polyaldehydcs such as polyoxymethylene, and the like. Additionally and even more preferably, one may incorporate the flame-retardant synergistic combinations mentioned above inuo such polymers as the styrene polymers, i.e. polystyrene, rx-methyl styrene polymers, etc. the a-olefin polymers, such as the homopolymers and copolymers etc. containing as the major constituent, thereof, ethylene, propylene, etc. including polyethylene, polypropylene and the like and the acrylic and methacrylic homopolymers and copolymers produced firom monomers having the formula wherein R is hydrogen or a methyl radical and R is hydrogen or an alkyl radical having from 1 to 6 carbon atoms, inclusive. Examples of monomers represented by Formula II include acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-amyl acrylate, t-amyl acrylate, hexyl acrylate and their corresponding alkyl rnethacrylates, etc.

Also such polymers as the nylons, e.g. adipic acidhexamethylenediamine reaction products; the cellulosics such as cellulose acetate (and/or butyrate, etc.), cellulose nitrate; the polycarbonates, e.g, phosgene-Bisphenol A reaction products; the so-called impact polymers, i.e. rubber-polymer blends such as blends of polystyrene With 510% of butadiene-styrene, etc. and the like may be made flame-retardant by the incorporation therein of the monophosphonium halide-chlorinated hydrocarbon synergistic combinations discussed hereinabove.

Examples of other monomers which may be used to form the thermoplastic vinyl polymers encompassed by the present invention, polymerized either singularly or in combination with each other or with the other compounds set forth hereinabove, are such monomers as the unsaturated ethers, e.g., ethyl vinyl diallyl ether, etc. the unsaturated amides, for instance, N-allyl caprolactam, arcylamide, and N-substituted acrylamides, e.g., N-methylol illustration only and are not to be construed as limitations on the present invention except as set forth in the appended claims. All parts and percentages are by weight unless otherwise specified.

acrylamide, N-allyl acrylamide, N-methyl acrylamide, N- Any appropriate flame-retardance test may be used to P y acfylamlde, the unsaturated ketOheS, -g' determine the flame-retardant properties of any specific methyl vinyl ketone, methyl allyl ketone, etc.; methylene combination of monophosphonium halide and chlorinated mal mC esters, e-g., methylene methyl mal nat t a d hydrocarbon material. One test I have found to be reasonthe like. ably efficient is a modified version of that test identified Other examples of polymers that may be employed 10 as ASTMD63556T. The specifications for this test are: are those of monomers set forth, for example, in U.S. a specimen, 5" in length, 0.5" in width and 0.045" in Patent No. 2,510,503, issued June 6, 1950. thickness is marked at the 1" and 4" lengths and is then The Production of thermoplastic resin Composltlons supported with its longitudinal axis horizontal and its which are flame-r tardant is of c nsider le commerci l transverse axis inclined at 45 to the horizontal. A Bunsen importance in that such articles as castings, moldings, bu r with a 1" blue flame is placed under the end of foamed or laminated articles, etc. are required, or at least th trip d i dju t d so that the flame tip is put in desired, to be resistant to firc and flame and to possess contact with the strip. At the end of 30 seconds, the flame the ability to endure heat without deterioration. Typical i ed d th specimen i allowed to burn. If the illustrations of applications of such compositions include specimen does not continue to burn after the first ignition, fiastihgs for live electrical Contacts which Should not he it is immediately recontacted with the burner for another lgfllted y llama of Sparks, Structural members such as 30 seconds. If, after the two burnings, the strip is not p P Wall coverings, Wall Paneling, Windows, eta and burned to the 4" mark, the specimen is designated as selfsuch items as ash trays, waste baskets, fibers and the like. extinguishing If th specimen is not burned to the 1" The novel flame-retardant combination claimed herein k i i designated as non-burning, In the modified y he added to the Various P y as such, or as test, the specimen is 20 mils in thickness rather than the individual components, by any known method. That is to prescribed 45" say, the flame-retardant components may be added to the EXAMPLE 1 polymer as such or in combination b (l) milling the polymer and the components, for exam ple, on a two-roll 100 Parts of polyPrqpylene are added part? of mill, in a Banbury mixer, etc. by (2) molding the commbut yl [2'(2'methyl'l'lmldatoyl) ethyl] phosphonulm ponents and the polymer Simultaneously, by (3) extrud chloride and 2.5 parts of chlorinated paraffin waxcontalning the polymer and components or by (4) merely b1end mg 70% chemically combined chlorine (emplrical foring all the materials together in powder or liquid form mllla C24H29Cl21) The resultant mlxture 1s Placed m a and thereafter forming the desired ultimate product. Addismtable blcnder dry'blended for 10 i The tionany the fiame retardant may be added during the blended product 1s then transferred to a melt-index appaduction of the polymer, i.e. during the monomer polymer- Tamas (See AST M D'123 62T) Wh 1ch 1S preheated. to ization, provided, however, that the catalyst, etc. other Followlng one mmutfi of agmg i conditions and other ingredients of the polymerization sys- 1s p f 0n e P u g r and an extrudate of 6-8 inches in tem am inert thereto. length is obtained. This specimen 15 marked and tested It is also within the scope of the instant invention to 40 according to the above-enumerated flame-retardance test. incorporate such ingredients as plasticizers, dyes, pig- The reults are Set forth Table ments, heat and light stabilizers, antioxidants, antistatic Vallous other flalfle'retardant FOmbmatIQHS are then agents, photochromic materials and the like into the polyincorporated into various other resins accordlng to Exammeric flame-retarded polymer compositions claimed here- F 1 and comparlsons are made between the resultant in. compositions and control compositions. These results are The following examples are set forth for purposes of also set forth inTable I, below.

TABLE I Ex. R R X Percent Chlorinated Percent Polymer Flame Test Hydrocarbon Results 1 n-Butyl 2-(2-methyl-1- CI 2.5 Chlorinated paraffin 2. 5 Polypropylene Passed.

imidazoyl) ethyl. 33:33? combined 12 13-.. Z-cyano-ethyl. 14 .do

Same as Ex. 1

24.- 25... Cyanomethyl 30 31. Naphthy Hexachlorobenzene Perchloropentacyclodecane.

. Same as Ex. 22 Clear polyphenyl resin:

Same as Ex. 28 Perehloropentacyclodecane.

diStillS, 280335 0.; softens, 98-105.5 C.

Same as Ex. 25 2,3,5,6-tetrachlorop-xylene.

- .do 1 o Poly(methyl- Passed.

methacrylate).

do Failed. Do

.do Polypropylene Passed.

TABLE I-Continued Ex. B. R X Percent Chlorinated Percent Polymer Flame Test Hydrocarbon Results 32 Naphthyl 2,4-dibromobenzyl Cl 15 Peirc'hloropentacyclo- Polypropylene Failed.

ecane.

Same as 31 15 .do Do. Hgnachlorocyclopenta- 3 Poly(vinylehloride) Passed.

iene.

d0.. Same as Ex. 34 6 do. Chlorinated parafiin 2.5

wax-40% combined chlorine.

do Failed.

Same as Ex. 37 do Do. Yellow viscous poly- 3.5 Polyethylene Passed.

phenyl oil: distills, 365-390f 0.; pours, 0.; refractive indexfi. 1.639-1541.

do Failed.

Same as Ex. 40 7.0 do Do. e,a-Dichlorom-xylene 5 Low density poly- Passed.

ethylene.

do Failed. Same as Ex. 43 10 do D White polyphenyl 4. 5 Polyoxymethylene powder: distills, 435-450 0.; softens, 150170 C.

Chlorinated paraflin wax-% combined chlorine.

53 do do Br 10. 0 i do 10 do Do. Same as Ex. 22 5. 0 Terpolymer of styrene, Passed.

aerylonitrile an methyl methacrylate (19/10/71). do Failed.

Same as Ex. 10 D Same as Ex. 6

Same as Ex. Same as Ex. 19

Same as Ex.

8-hydroxyoctyL .s

1 Adipie acid-hexamethylenediamine reaction product. 2 D-line at 20 C. I claim: 1 wherein (2) is methyltris(Z-cyenoethyl) phosphonium 1. A flame-retardant composition comprising 1) a bromide. chlorinatfid hydrociilrbon contaiPing 4. A flame-retardant composition according to claim 1 of combined chlorine and having a bolhng point of at 55 wherein (1) is achlorinated paraffin 1ea$t200 a monophosphonium halide having 5. A flame-retardant composition according to claim the formula 1 wherein (1) is a polychlorinated cyclic hydrocarbon.

R 6. A flame-retarded composition comprising a thermog plastic polymer having incorporated therein a flame-retarding amount of the composition of claim 1 the sum (m3 of the flame-retarding amounts of components (1) and wherein R is selected from the group consisting of alkyl being less than those P P Which F c c cyanoalkyl 43 ary] 3 43 lk l ponent (1) or (2 functions indlvidually in a flame- (CTC 11) or hydroxyalkyl (CF08) radicals and=R1 is retarding manner similar to the combmatlon 1n the same lected from the group consisting of alkenyl (C -C di- 5 p y to which the combmatlqn 18 addedalkylaminoalkyl (C -C carboalkoxyalkyl (C -C car- A ifiamF-retarded COIIIPOSIUOII afcordlng t0 clalm boxyalkenyl (C C carboalkoxyalkenyl (C -C imid 6 -where1n sald thermoplastic polymer is a polyolefin. azoylalkyl (C C carboxyalkyl (C -C alkyl (C 43 8. A flame-retarded composition according to clann 6 cyanoalkyl c -c hydroxyalkyl 3 4 and alkyl wherein said thermoplastic poly er is polyethylene. (C7-C11) radicals and X is selected from the group oonfiafne-retal'ded cqmposltwn flccordlng t0 6131111 6 sisting of bromine, chlorine and iodine. Wherelfl 531d thermoplastic E 1S p y Ppy 2. A flame-retardant composition according to claim 1 flame-retarded cofnposltloll according to Clalm wherein (Z) is 2-4-dichlorobenzyltriphenyl phosphonium 6 wherein 531d I P P y 15 P y y chloride.

3. A flame-retardant composition according to claim (Referen es on f ll i page) References Cited MORRIS LIEBMAN, Primary Examiner.

UNITED STATES PATENTS 3,214,434 10/1965 Grayson et a1 10615 S-L-FOXASSIWMEMWW- OTHER REFERENCES 5 US. Cl. X.R.

Modern Plastics, October 1964, vol. 42, N0. 2, pp. 86, 87, 88, and Table on p. 89. 

